Voltage regulating system



Nov. 7, 1961 G. N. OTTON 3,008,084

VOLTAGE REGULATING SYSTEM Filed Aug. 4, 1958 3O INPUT VOLTAGE 34 OUTPUT 35 FIRST sues a7 REGULATING ACTI( I 4 36 sacouo snca OUTPUT secono STAGE TIME FIG. 3

INVENTOR. GILBERT N. COTTON BY I ATTORNEYS United States Patent Ofiiice 3,008,084 Patented Nov. 7., 1961 3,008,084 VOLTAGE REGULATING SYSTEM Gilbert N. Cotton, Parana, ()hio (2522 15th St, Cuyahoga Falls, Qhio) Filed Aug. 4, 1958, Sler. No. 752,826

3 Claims. (Cl. 323-75) This invention relates to a very accurate voltage regulating system in which a plurality of resistor bridges are used with the dynamic impedance of the zener reference diodes balanced out by said resistor bridges.

The invention further relates to a two stage voltage regulator circuit in which the output of the first stage is the input to the second stage resistor diode bridge.

'In general in connection with voltage regulator circuits, a number of zener voltage regulators have been used and the ability of these voltage regulators to regulate the output voltage to 0.01 percent or in some extreme cases even 0.005 percent make them ideally suited to certain applications particularly in regulated power supplies, transistor circuits, etc.

This invention particularly relates to a voltage regulating system in which a two stage resistor bridge is used with zener diodes in each of the bridges providing regula tion to 0.000001 percent or less. Further, the system is capable of accepting a change in input voltage (AEi) which is at least 400 percent of the minimum input voltage without an observable change in output voltage (AEO) Many devices can only Work in a range of or 13 percent input voltage change and then are able to reduce this to only a 0.01 percent change in output voltage. Regulation is herein defined as AEo AEi

An object of this invention is to provide a new and improved resistor bridge voltage regulating circuit using zener diodes.

A further object of this invention is to provide a new and improved voltage regulating system using a resistor bridge with a zener diode in one leg of the bridge for feeding the input to a second stage which uses a similar resistor diode bridge and provides a very accurate voltage output because of near perfect overall regulation.

A further object of this invention is to provide a reference voltage so accurate and stable that it becomes a new source of standard reference voltage that has many advantages over the present wet-cell type of standard.

To the accomplishment of the foregoing and related ends, said invention then consists of the means hereinafter fully described and particularly pointed out in the claims; the following description setting forth in detail one approved means of carrying out the invention, such disclosed means, however, constituting but one of the various ways in which the principles of the invention may be used.

In the drawings:

FIG. 1 is a schematic diagram of a resistor bridge zener diode voltage regulating system;

FIG. 2 is a diagrammatic presentation of a circuit of this invention; and

FIG. 3 shows the input voltage versus time and illustrates 1) the extreme case of a step function change in input voltage, (2) the regulating action of the first and second stage, and (3) the output of the second stage.

This invention is a voltage regulating system using resistor bridges in which the dynamic impedance of the zener diode is balanced out by the resistor bridge and the imperfect regulation of the first bridge cancelled by the mirror image action of the second bridge.

FIG. 1 shows the schematic view of this invention in which the line voltage is put across the terminals L and L at 10 and 11. The resistances R and R are shown at 12 and 13, respectively, and the zener diode indicated Z at 14 completes with the resistance R at 15 to bridge the circuit. This circuit may be used with double anode zener diodes. However, these would be used to ensure a low temperature coeificient of voltage. The circuit works equally as Well with ordinary zener diodes.

The second stage of the regulator is similar to the first stage. The output of the first stage is placed across the input of the second stage. The output terminals of the first stage, therefore, are indicated at 16 and 17, and these are put into the input terminals of the second stage at 18 and 19, respectively. There are in this second bridge similar resistances indicated R R and R7 and Z for the zener diode, and these are at 20, 21, 22 and 23, respectively. In the output circuit from this are the terminals 24 and 25 and to the final output terminals 25 and 26. In the connection between terminals 24 and 25 is a resistance shown at 2.7. With 27 in circuit, current is made constant as well as voltage, and a standard open circuit voltage is provided.

If the first stage, as shown in FIG. 1, is balanced and the impedance Z constant, then E0 at 16 would be constant and independent of input voltage changes. However, if the impedance Z were not constant which results in a change in the output voltage, i.e., reversed in polarity to the change in input voltage, it must be concluded that Z increases or decreases from the static value. The increase or decrease of Z is dependent upon the polarity of the input voltage change. The change in E0 under consideration here is a short term change, as shown in FIG. 3, since the voltage docs. return to the original value withi: the long term regulation capability of the circuit after a certain time lapse.

By the addition of a second stage to the first stage, a short term change in voltage will not appear at the output of the second stage. The reason for this is that the cascading of an even number of stages, which individually have a reversal of polarity in the regulation on a short term basis, results in a complete cancellation of the short term effect. The addition of the second stage also improves the long term regulation.

This may be clearly seen in connection with FIG. 3, where the input voltage at 30 will drop suddenly as. at 31 to a new value as at 32 over the time interval indicated until the step finishes as at 33. This results in a short term voltage change, which is the output of the first stage and is indicated by the curve shown at 34 and commences at the same instant of time as the step 31. The change on the reversal will be the mirror image of the first change as indicated at 35. By causing the output of the first stage to be across the input terminals of the second stage, the regulating action of the second stage will be the mirror image of the change in the first stage, and this voltage wave form is indicated at 36 and 37. The regulated output of the second stage is as indicated by the straight line 38.

FIG. 2 shows a typical circuit involving this invention in which volt A.C., 60 cycle, is put across a Variac 4-0 connected to an isolating transformer shown generally at 41 having a ratio of 110120 and a resistance in the line, together with a rectifier such as IN93 indicated at 42, and a typical condenser such as a 50 microfarad, 60 volt tantalytic condenser indicated at 43.

The remaining elements of the circuit could be compared in order but they are substantially similar to those of FIG. 1. Further descriptions of this invention seem unnecessary, and FIG. 2 is only illustrative of the use of this invention.

Typical double anode zener diodes suitable for use in this invention are types IN229, IN430, etc.

Although the present invention has been described in connection with a few preferred embodiments thereof,

variations and modifications may be resorted to by those skilled in the art without departing from the principles of the invention. All of these modifications and varia tions are considered to be within the true spirit and scope of the present invention as disclosed in the foregoing description and defined by the appended claims.

I claim:

1. In a zener diode resistance bridge, a first stage resistor bridge having an input voltage and a zener diode in one of the legs of said bridge, whereby the dynamic impedance of the first Zener diode is balanced out by the first resistor bridge, and the output terminals connected to the input terminals of a similar bridge having a zener diode similarly positioned, whereby the dynamic impedance of the second zener diode is balanced out by the second resistor bridge.

2. In a voltage regulating circuit of a resistance type bridge having zener diodes as one leg of said bridge, a first stage resistance bridge in which the output of said first stage is fed to the input of a second stage resistance bridge in which the Zener diode resistance is similarly positioned, and in which any imbalance in the impedance of the zener diode results in a reversal of polarity of the input voltage in the output voltage of the first stage, and in which the second stage efiectively cancels said reversal of polarity so that the output of the second stage is a constant voltage.

3. The zener diode resistance bridge of claim 1, in which a resistance is placed in one of the output terminals, whereby a standard open circuit reference voltage is provided in which the current is constant as well as the voltage.

References Cited in the file of this patent UNITED STATES PATENTS 2,864,053 Woodworth Dec. 9, 1958 

